Ultra‐White Elastomeric Coatings for Daytime Radiative Cooling

ABSTRACT Elastomeric coatings with >100% elongation are often required for cool‐roof systems, yet their solar reflectance is below 90% due to intrinsic UV absorption in TiO 2 pigments and near‐infrared (NIR) absorption in conventional binders, preventing sub‐ambient daytime radiative cooling. Here, we report highly elastic radiative cooling coatings that overcome these limitations, by combining wide‐band‐gap pigments (BaSO 4 , CaCO 3 , hBN) with a low‐absorptance silicone elastomer binder. This design minimizes solar absorption while maintaining stretchability even at high pigment volume fractions. The resulting elastomeric coatings based on BaSO 4 , CaCO 3 and hBN achieve high solar reflectance of 95.3%, 94.6%, and 93%, along with strong sky window emissivity of 0.956 ± 0.010 for all elastomers, enabling daytime sub‐ambient cooling of 1.9°C, 2.1°C, and 1.3°C, respectively. All formulations exhibit >100% elongation, with elastic moduli of 6.72, 0.126, and 3.026 MPa. The silicone matrix imparts pronounced surface hydrophobicity with water contact angles up to 153.9° and, combined with UV‐stable fillers, demonstrated retention of high solar reflectance after accelerated UV aging, confirming strong UV durability. This work establishes a scalable approach to radiative cooling elastomeric coatings, enabling sub‐ambient performance in applications requiring mechanical stretchability.